In an optical amplifier that includes a solid-state laser medium, an active element (such as a rare earth element or a transition metal element), contained in the solid-state laser medium, is pumped by illumination of the pumping light outputted from a pumping light source. In this process, emission light with a predetermined wavelength is generated by a stimulated emission phenomenon inside the solid-state laser medium. A laser oscillator is constituted by such an optical amplifier and an oscillator. For example, when the solid-state laser medium is Yb-doped YAG, the pumping light source is a laser diode and the wavelength of the light that can be amplified is 1030 nm.
In an optical amplifier or a laser oscillator with such a structure, the solid-state laser medium generates heat during operation. The solid-state laser medium must thus be heat-released or cooled to achieve stable operation and obtain a high-quality optical output. For example, a laser oscillator disclosed in a Patent Document 1 includes a solid-state laser module constituted by a polycrystalline transparent ceramic that does not contain an active element, a solid-state laser medium (a polycrystalline transparent ceramic doped with an active element) that is in contact with the polycrystalline transparent ceramic, and a heat sink disposed so as to hold these components simultaneously. In the solid-state laser module with this arrangement, the heat generated at the solid-state laser medium propagates through the polycrystalline transparent ceramic, which does not contain the active element, and the heat sink, and temperature rise of the solid-state laser medium is thereby suppressed.
Patent Document 1: Japanese Patent Application Laid-Open No. 2002-57388